Kerri Evelyn Harris' secret weapon in her upstart Democratic campaign for a U.S. Senate seat is size — or, more specifically, Delaware's lack of it.

The First State is, after all, also America's second-smallest state, in terms of square miles. It's the kind of place where an anonymous arm juts out from a soul-food truck with a Styrofoam platter of fried chicken and fish as newcomer candidate Harris strolls by on a downtown Wilmington sidewalk, or where a voter starts his complaint about the incumbent Democrat Sen. Tom Carper with what happened when they ran into each other in the supermarket.

In a big state like Pennsylvania, politics may have become an air battle of TV-ad carpet bombing from 30,000 feet, but elections in Delaware are still a form of urban warfare, waged from house-to-house in close quarters. That makes it the kind of place where an unconventional candidate like Harris — who, in telling a group of voters about her Air Force experiences as an Iraq War veteran, calls herself "a whole lot of otherness" — can meet and greet enough voters to have a serious shot at ousting a three-term incumbent like the 71-year-old Carper, a Delaware institution.

If she can upset Carper in next Thursday's primary and then win in November against underwhelming GOP opposition, the 38-year-old Harris would be the First State's first woman, first black, and first openly LGBTQ U.S. senator. More importantly, a Harris victory would take a proverbial sledgehammer to the decades-old Delaware Way — the weird form of gentlemanly (and, yes, they're almost all gentlemen) consensus that is socially liberal but aggressively pro-business and pro-bank and often pro-polluter policies, as defined by career pols like Carper and former vice president Joe Biden and the occasional benevolent billionaire like former governor Pierre "Pete" Du Pont.

WILL BUNCH / STAFF

U.S. Senate candidate Kerri Evelyn Harris at her campaign office in Wilmington.

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In a past, "normal" election year, an underdog candidate like Harris might have been seen mainly as a curiosity … but little more. But things are not normal in 2018. For Democrats, the shock of Donald Trump's election on Nov. 8, 2016 not only pulled passive voters off the sidelines but has caused them to question many of their basic political assumptions of the last 30 or so years. Like, why do we spend so much on mass incarceration, or a never-ending "war on terror"? Where's the return on investment in robotically sending careerist centrists like Carper back to Washington every six years.

They saw arguably the most unassuming U.S. Senate candidate in America right now — khaki pants, teal polo shirt, short, almost-military-style hair, no makeup, no jewelry other than the big watch that struggles to keep her on-time for a half-dozen events every day. She doesn't even wear a campaign button. A former auto-body mechanic, Harris takes a nuts-and-bolts approach to politics — shunning gimmickry for big ideas and relatable anecdotes, like how a minimum wage worker in Delaware has to toil for two hours just to buy the same off-brand diapers that Harris, a mother of two, buys for her 1-year-old son.

"We need new ideas," she told the Bellefonte attendees. "We need a sense of urgency. We can't be told, 'Not this year it's an election year, or not right now it's not a popular issue, or wait a little bit longer.' People are dying. People are hungry. People are afraid we're not a community of neighbors anymore. We avoid speaking with their neighbors because they voted for that guy …"

WILL BUNCH / STAFF

U.S. Senate candidate Kerri Evelyn Harris speaks to voters at a cafe in Bellefonte.

She said her campaign isn't anti-Trump, anti-GOP or even anti-Carper, but all about how to accomplish positive things such as raising the minimum wage to $15 without hurting small businesses, achieving true universal health care, and wiping out college debt. That didn't mean there weren't sharp exchanges with Carper in Monday's debate, especially over the cost of paying off those student loans. The incumbent said told Harris "there's no magic wand" to find the money.

"Nobody asked how we were going to pay for sending myself and other veterans into war in Iraq," Harris told the Bellefonte meet-and-greet, drawing nods and affirmations. Most of the attendees have voted in the past for Carper, who's also been governor and a congressman during his long career. Most are having second thoughts, if they aren't already committed to newcomer Harris.

"He's out of touch — he's been in an office too long," Aniela Meinhaldt told me. "Maybe 20 years ago he was fine." She said her husband Kevin didn't get much help from Carper's office over his issues with the Veterans Affairs Department, and she cited his ties to Big Pharma and insurance companies. Others said they were now thinking negatively — sometimes with a friendly prod from the Harris campaign — about Carper's vote for the Keystone XL oil pipeline, his support for the Iraq War and other U.S. militarism, and his role in boosting prison spending when he was governor.

"He voted for the 'three strikes' law [on repeat felons], I don't like that — it disproportionately affected black people," JoAnn Means, a 41-year-old Wilmington woman told me at Peace in the Streets, an outdoor music event on the Christina River waterfront where Harris mingled among the crowd, hugging attendees who know her as a community organizer.

WILL BUNCH / STAFF

Wilmington voter JoAnn Means.

James Butcher, who runs a Wilmington food program for the homeless called Endless Line, said his clients were shocked when Harris paid a visit at lunchtime — so much so that some of them went out and registered to vote. It was a typically unconventional move for a candidate with an unconventional background, who ended up in Dover after leaving the Air Force in 2008 for medical reasons and sold fried chicken in a gas station for a time before finding new life around community organizing on issues such as education and the opioid crisis.

Harris told me in an interview that she'd expected someone else to challenge Carper, that "I always like to be in the background," as a staffer. But then she thought she'd be "a hypocrite" if she didn't step forward after no one else did. "If Trump was able to energize a base to go out and vote, whereas we [Democrats] just made people stay home, what was wrong?" she asked.

Her path to victory looks similar to the road traveled by Gillum and Ocasio-Cortez — expand the electorate by persuading more young people, non-whites and disaffected progressives to vote in the midterms. That's a slightly easier equation in a place like Delaware, where in-person, or retail, politics still matters and Harris believes she can win with just 26,000 votes.

The early line on next Thursday's balloting — with little polling in the race — is that there's a surprisingly high level of undecided voters but that Carper's high name ID and his huge money advantage will be very tough to overcome.

After spending time on the campaign trail in Delaware, I wasn't yet fully convinced that Harris could pull that huge upset, but I was certain that the Democratic Party of Carper and Joe Biden's 20th Century is fading fast, with the party's base now openly questioning all of the things — curbs on marijuana and the cost of "the war on drugs," long prison sentences, militarism in the Middle East and unfettered capitalism — that were once not to be questioned. The biggest question for Kerri Evelyn Harris may be whether she's just slightly ahead of her time.